Cleavage | n. 1. The act of cleaving or splitting. [ 1913 Webster ] 2. (Crystallog.) The quality possessed by many crystallized substances of splitting readily in one or more definite directions, in which the cohesive attraction is a minimum, affording more or less smooth surfaces; the direction of the dividing plane; a fragment obtained by cleaving, as of a diamond. See Parting. [ 1913 Webster ] 3. (Geol.) Division into laminæ, like slate, with the lamination not necessarily parallel to the plane of deposition; -- usually produced by pressure. [ 1913 Webster ] Basal cleavage, cleavage parallel to the base of a crystal, or to the plane of the lateral axes. -- Cell cleavage (Biol.), multiplication of cells by fission. See Segmentation. -- Cubic cleavage, cleavage parallel to the faces of a cube. -- Diagonal cleavage, cleavage parallel to ta diagonal plane. -- Egg clavage. (Biol.) See Segmentation. -- Lateral cleavage, cleavage parallel to the lateral planes. -- Octahedral cleavage, Dodecahedral cleavage, or Rhombohedral cleavage, cleavage parallel to the faces of an octahedron, dodecahedron, or rhombohedron. -- Prismatic cleavage, cleavage parallel to a vertical prism. [ 1913 Webster ]
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